Two lines of murine tissue culture cells transformed by polyoma virus have an extra peak of a specific amino acid accepting tRNA upon chromatography on benzoylated DEAE-cellulose, whereas the parent cells, and cells from mouse embryo and mouse liver, have only two peaks of tRNA accepting that amino acid. The extra peak has been well characterized as a real peak and not an artifact of chromatography or isolation. The extra peak or a similar peak may appear in small amounts in other DNA and RNA virus-transformed cells; however, polyoma-transformed cells always seem to have appreciable quantities of the extra peak. Since an effect of different media has been noted, further work to characterize the media effect will be done. Additional work to clarify an aminoacylation anamoly will be done; there seems to be a preference for aminoacylation of the extra peak under limiting enzyme conditions. Functional studies of the extra peak will be initiated: codon response, participation in protein synthesis.